The present invention relates generally to an automatic shutoff valve. More particularly, the present invention relates to a valve and fuel tank assembly for controlling fuel vapor from entering the atmosphere during operation or shutdown of a fuel supply system.
In a typical fuel supply system, such as a fuel supply system associated with gasoline powered engines, it is desirable to seal the fuel outlet while the engine is shut down, thereby prohibiting harmful vapor as well as inadvertent fuel to escape into the atmosphere. Further, in a typical fuel supply system, it is desirable that the fuel outlet be responsive to a vacuum created in the fuel line.
In order to prohibit vapor and fuel from egressing from the fuel receptacle while not in use, many techniques have previously been employed. For example, in the most simple mechanical scenario, a valve can easily be incorporated which can be manually closed. While this technique is effective, it is inherently associated with numerous drawbacks including, but not limited to, operator error or forgetfulness and inconvenience, especially where the fuel source is remotely located relative to the engine controls.
It has also been previously proposed to provide a valve for a fuel receptacle which is responsive above a predetermined negative pressure or vacuum on the engine side of the valve. However, such valves heretofore incorporated can be opened by a positive pressure equal in magnitude located on the fuel receptacle side of the valve. This makes the tank susceptible to pop-off or breakaway when the receptacle contents exceeds a given pressure, and thereby allows fuel and vapor to be released into the atmosphere.
Accordingly, it is desired to provide a valve design which overcomes the above-discussed problems inherently associated with the prior art by providing an improved valve for fuel supply systems that automatically opens in response to negative pressure on the engine side of the valve, but will not open in response to positive pressure produced on the fuel receptacle side of the valve. The present invention provides such a valve for use in supplying fuel from a fuel source to an internal combustion engine.
Thus, it is a principal object of the present invention to provide an assembly for a fuel supply system which is responsive to negative pressure produced by the engine, but which is resistant to positive pressures which may develop in a fuel receptacle.
It is a related object of the present invention to provide an assembly for a fuel supply system which automatically prohibits vapor from escaping from a fuel receptacle upon engine shutoff.
It is yet another object of the present invention to provide a fuel supply assembly which vents to atmosphere in one direction during engine operation and seals the fuel and fuel vapor from entering atmosphere during engine operation as well as during engine shut down.
It is yet a further object of the present invention to provide an assembly through which the fuel flows in the same direction as the valve moves to shut off flow through the assembly, so that pressure will be contained infinitely.
From the subsequent detailed description taken in conjunction with the accompanying drawings and subjoined claims, other objects and advantages of the present invention will become apparent to those skilled in the art.